Flexible corrosion-inhibiting cover for a metallic object

ABSTRACT

A cover ( 200 ) for inhibiting corrosion of a metallic object over which the cover is placed. The cover has an inner surface ( 104 ) defined by a liquid-permeable layer ( 202 ) and an outer surface ( 102 ) defined by a liquid-impermeable layer ( 204 ). A moisture-absorbing layer ( 206 ) is sandwiched between the liquid-permeable layer and the liquid-impermeable layer. The liquid-permeable layer allows vapor and liquid moisture beneath the cover to be absorbed into the moisture-absorbing layer to reduce the amount of moisture beneath the cover. The liquid-impermeable layer repels environmental liquid moisture, such as rain, sea spray, dew and the like and prevents such moisture from penetrating the cover. A radar-influencing layer ( 308 ) and vapor corrosion inhibitors ( 214 ) may be included in the cover. A method of protecting an object is also disclosed. The method includes covering a metallic object with cover ( 200 ).

This invention was made with Government support under contractN00024-99-C-4107 awarded by the U.S. Navy. The Government has certainrights in the invention.

FIELD OF THE INVENTION

The present invention generally relates to the field of covers forprotecting materials from environmental elements. More particularly, thepresent invention is directed to a flexible cover that actively inhibitsthe corrosion of a metallic object on which the cover is placed.

BACKGROUND OF THE INVENTION

Corrosion and corrosion mitigation have become increasingly importantfor economic and safety reasons. Based on estimates made in the mid1990's , overall costs attributable to corrosion account for over $100billion a year in the United States alone. These costs typically accountfor only the direct costs of corrosion and do not include the associatedindirect costs, such as safety, plant downtime, loss of product,contamination and over-design.

Corrosion is defined as the destructive result between a metal or metalalloy and its environment. Nearly every metallic corrosion processinvolves the transfer of electronic charge in aqueous solution, and mostcorrosion reactions take place in the presence of water in either liquidor condensed vapor phases and also in high humidity.

Corrosion is particularly a problem in marine environments, such asshipboard, off-shore drilling rigs, coastal regions and the like, whereseawater enhances corrosion reactions due to increased ion transport, pHeffects and elevated dissolved oxygen levels that in turn enhance levelsof hydrogen ions. Corrosion reactions are further accelerated in marineenvironments by contaminants, such as chloride ions, present inseawater. Corrosion damage to equipment stored and used in marineenvironments is a tremendous problem, impacting maintenance costs,availability, repair and reliability.

Equipment stored, for example, onboard a ship or in coastal regions, isoften stored in protective storage systems that have proved to be lessthan optimally effective. At best, such equipment is covered withwaterproof tarpaulins, although often, especially for shipboardequipment, it is not stored properly and is directly exposed to a marineenvironment, which leads to rapid corrosion. Even when equipment iscovered by waterproof tarpaulins, seawater still penetrates throughand/or around the tarpaulins into the protected spaces where it collectsand corrodes the underlying equipment. Also, conventional storagesystems can be cumbersome to use and maintain, and are often avoided. Asa result, corrosion continues to be a significant and costly problem,requiring many hours of rust removal, painting and repair that lead topremature equipment replacement.

FIG. 1 shows a conventional waterproof cover 20 used to protect metallicobjects, such as metallic block 22 shown resting on a surface 24, frommoisture, such as rain, sea spray, dew and the like. Cover 20 has anouter surface 26, an inner surface 28 and an area 30 defined by aperipheral edge 32. Cover 20 is shown covering block 22 in a typicalmanner, wherein a micro-environment, is generally defined by the spaceenclosed by cover 20. The micro-environment comprises a number ofinterior regions, such as regions 34, located between cover 20 and block22.

Generally, prior art covers comprise at least one liquid-impermeablelayer made of, for example, a tightly-woven polymer fabric. More complexprior art covers may include one or more additional layers that providethe inner surface with a non-abrasive texture to minimize mechanicaldamage to the object covered. Other prior art covers are made ofvapor-permeable materials, such as expanded polytetrafluoroethylene orthe like.

Interior regions 34 generally never have a moisture content less thanthat of the ambient environment. If the moisture content of the ambientenvironment rises, the moisture content of regions 34 also rises due tothe inflow of moisture (illustrated by arrow 36) through gaps betweencover 20 and surface 24 at peripheral edges 32. Eventually, the moisturecontent of the ambient environment 38 and regions 34 equalize. Once theadditional moisture is in the micro-environment, it can become trapped,as illustrated by arrows 40. Moisture levels can quickly become elevatedand the air saturated. In such a case, condensation could occur on theblock 22. Because the moisture content of interior regions 34 neverfalls below that of ambient environment 38, prior art covers are notvery effective in high moisture environments, such as marine andhigh-humidity environments. Moreover, once moisture enters themicro-environment, it can take a long time to dissipate, if at all.

SUMMARY OF THE INVENTION

The present invention is directed to a cover for inhibiting corrosion ofa metallic object. The cover includes a first layer having a first faceand a second face. The first layer comprises a super-absorbent materialadapted to absorb and store moisture. A second layer is located adjacentthe first face of the first layer. The second layer is liquid permeable.A third layer is located adjacent the second face of the first layer.The third layer is liquid-impermeable. A radar-influencing layer islocated within or adjacent at least one of the first layer, second layerand third layer. The radar-influencing layer comprises aradar-influencing material.

In another aspect, the cover of the present invention includes a firstlayer having a first face and a second face. The first layer comprises asuper-absorbent material adapted to absorb and store moisture. A secondlayer is located adjacent the first face of the first layer. The secondlayer is liquid permeable. A third layer is located adjacent the secondface of the first layer. The third layer is liquid-impermeable. A vaporcorrosion inhibitor layer is located within or adjacent at least one ofthe first layer, second layer and third layer. The vapor corrosioninhibitor layer comprises a vapor corrosion inhibitor.

In yet another aspect, the cover of the present invention includes apanel having a first face, a second face and a peripheral edge. Thepanel includes a first layer having a first face and a second face. Thefirst layer comprises a super-absorbent material adapted to absorb andstore moisture. A second layer is located adjacent the first face of thefirst layer. The second layer is liquid permeable. A third layer islocated adjacent the second face of the first layer. The third layer isliquid-impermeable. The panel includes a fastening means locatedadjacent the peripheral edge adapted to removably fasten said panel to asimilar panel.

The invention is also directed to a method of inhibiting corrosion on ametallic object. First, a cover is provided. The cover includes a firstlayer having a first face and a second face.

The first layer comprises a super-absorbent material adapted to absorband store moisture. A second layer is located adjacent the first face ofthe first layer. The second layer is liquid permeable. A third layer islocated adjacent the second face of the first layer. The third layer isliquid-impermeable. Next, at least a portion of the metal object iscovered with the cover such that the second layer faces the object.

BRIEF DESCRIPTION OF THE DRAWINGS

For the purposes of illustrating the invention, the drawings show a formin which the invention may be embodied. It should be understood,however, that the invention is not limited to the precise arrangementsand instrumentalities shown.

FIG. 1 is a cross-sectional view of a prior art cover shown covering anobject;

FIG. 2 is a cross-sectional view of a corrosion inhibiting cover of thepresent invention shown covering an object;

FIG. 3 is a cross-sectional view of a portion of one embodiment of thecorrosion inhibiting cover of the present invention,

FIG. 4 is a cross-sectional view of a portion of an alternativeembodiment of the corrosion inhibiting cover of the present invention;

FIG. 5 is an enlarged view of one edge of the cover shown in FIG. 2, forone specific embodiment of the present invention;

FIG. 6 is a perspective view showing an embodiment of the corrosioninhibiting cover of the present invention comprising a plurality ofpanels removably secured to one another; and

FIG. 7 is an enlarged cross-sectional view of one of the peripheraledges of one of the panels taken along line 7—7 of FIG. 6.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings, wherein like numerals indicate likeelements, FIG. 2 illustrates a corrosion-inhibiting cover, which isgenerally denoted by the numeral 100. Cover 100 is preferably made offlexible materials and includes an outer surface 102 and an innersurface 104. In some cases rigid materials, often formed with aconfiguration corresponding to that of the object to be covered, may beused for cover 100. Cover 100 has a peripheral edge 106 that defines anarea 108, which may be shaped as desired to suit a particularapplication. When draped over an object, such as a metallic block 110resting on a surface 112, outer surface 102 is exposed to an ambientenvironment 114 and inner surface 104 defines a micro-environmentcomprising a number of interior regions, such as those denoted as 116,located between inner surface 104 and block 110.

Although metallic block 110 is generally protected from elements presentin ambient environment 114 by cover 100, moisture from ambientenvironment 114 tends to infiltrate (as illustrated by arrow 118)interior regions 116 through gaps between peripheral edge 106 of cover100 and surface 112. However, the materials and structure of cover 100allow it to absorb and store such infiltrating moisture (as illustratedby arrows 120) from within interior regions 116 and maintain themoisture content of the micro-environment at a low level, below that ofambient environment 114. Cover 100 is also able to absorb and store bywicking action any water present on the surface of block 110 that comesinto contact with inner surface 104. This low-moisture micro-environmentinhibits metallic block 110 from corroding. In addition to the abilityto absorb and store moisture, cover 100 may be provided with the abilityto passively regenerate its moisture-absorbing and storing features byallowing stored moisture to diffuse to the outer surface of the cover,where it can evaporate (as illustrated by arrows 122) into ambientenvironment 114 when conditions there are suitable for evaporation.

Beneficial features of the flexible cover 100 of the present inventionare that it can be made to any size and shape necessary to protect anobject having virtually any size and surface profile. Some diverseexamples of such objects are containers for container ships,deck-mounted guns on naval ships, construction equipment, storedconstruction materials, air conditioning units and barbeque grills, toname just a few. Pouches of flexible cover 100 could be fashioned tostore munitions, tools, handguns and telephones and other electronicdevices to name just a few. One skilled in the art will recognize thatthere is a vast range of applications for cover 100.

Referring now to FIG. 3, there is shown one specific embodiment ofcorrosion-inhibiting cover 100 of the present invention, which isidentified at 200. Cover 200 comprises three layers consisting of aliquid-permeable layer 202, a liquid-impermeable layer 204 and amoisture-absorbing layer 206 sandwiched between liquid-permeable layer202 and liquid-impermeable layer 204. With reference to FIGS. 2 and 3,liquid-permeable layer 202 forms inner surface 104 of cover 200 andretains the constituent materials of moisture-absorbing layer 206 withincover 200. Liquid-permeable layer 202 is vapor permeable to allowmoisture vapor within interior regions 116 to reach moisture-absorbinglayer 206, and liquid-permeable to allow any liquid water contactinginner surface 104 of cover 200 to be wicked into moisture-absorbinglayer 206. Preferably, liquid-permeable layer 202 has a watertransmission rate of greater than 10 g/m²-hr. Liquid-permeable layer 202should be made of a durable woven or non-woven material that canwithstand repeated use and continual contact with a wide variety ofsurfaces. It is also preferable that liquid-permeable layer 202 berelatively smooth and/or soft so that damage to any object contacted byliquid-permeable layer 202 is avoided. A preferred material forliquid-permeable layer 202 is polyester mesh Style No. 9864, availablefrom Fablock Mills, Murry Hill, N.J. Other suitable materials includenylon, polypropylene, or the like and are available from Fablock MillsInc., Murry Hill, N.J., Jason Mills Inc., Westwood, N.J., and ApexMills, Inwood, N.Y. among others.

Moisture-absorbing layer 206 includes a fiber matrix 210 and asuper-absorbent material 208, such as hydrogel. Preferably, thesuper-absorbent material 208 is in particulate or fiber form, whichallows it to be dispersed throughout the fiber matrix. Alternatively,however, super-absorbent material 208 may be located in a generallydiscrete layer within fiber matrix 210, which may comprise either awoven or non-woven material. Examples of acceptable materials for fibermatrix 210 include wool, fiberglass, polymer fleece, fluff wood pulp andthe like. It is desirable that fiber matrix 210 have a high capillarity,preferably greater than 10 g/m²-hr., so that moisture coming intocontact with moisture-absorbing layer 206 through liquid-permeable layer202 may be wicked deep into moisture-absorbing layer 206 to takeadvantage of the super-absorbent material located there. Although afiber matrix is shown, it may be eliminated in an alternative embodimenthaving a hydrogel or other super-absorbent material in a form that neednot be supported by and/or located within a fiber matrix.

Hydrogel, one example of a class of super-absorbent materials, iscapable of absorbing up to 400 times its weight in water. With such alarge absorption capability, the particles of hydrogel can swell to manytimes their original size. If the hydrogel particles are not distributedproperly throughout fiber matrix 210, moisture-absorbing layer 206 mayexperience hydroblocking, wherein the hydrogel particles closest to themoisture source swell so much that they block moisture from being wickedfarther into the fiber matrix. Although some of the absorbed moistureeventually reaches the hydrogel located deep within fiber matrix 210 bydiffusion, diffusion is a slow process that would degrade the usefulnessof a cover experiencing hydroblocking, particularly in high-moistureconditions. Therefore, care must be taken to distribute super-absorbentmaterial 208 within fiber matrix 210 in a manner such that when thesuper-absorbent material adjacent the mesh layer is saturated, the fibermatrix is still able to wick water deeper into the moisture-absorbinglayer.

Liquid-impermeable layer 204 defines outer surface 102 of cover 200 andprevents liquid in ambient environment 114, such as rain, sea spray, dewand the like, from reaching interior regions 116 beneath the cover. Itis preferable, however, that liquid-impermeable layer 204 bevapor-permeable material to allow moisture stored in moisture-absorbinglayer 206 to escape into ambient environment 114 by diffusion andevaporation as described above. Preferably, liquid-impermeable layer 204has a vapor transmission rate of greater than 1 g/m²-hr. The liquidtransmission rate through the liquid-impermeable layer 204 should beless than the employed vapor transmission rate for the liquidimpermeable layer. For the stated lower bound of 1 g/m²-hr. of vaportransmission through the liquid-impermeable layer 204, a liquidtransmission rate through the liquid-impermeable layer 204 could be anyvalue less than 1 g/m²-hr. If the vapor transmission rate were greater,the corresponding acceptable level of liquid transmission would begreater, as long as it remained less than the vapor transmission rate.By allowing stored moisture to escape, cover 200 is capable ofregenerating itself during periods of low ambient moisture so that it iscapable of storing more moisture during a subsequent period wheninterior regions 116 again become moisture laden. Beneficially, theliquid-impermeable layer should also be able to absorb solar energy toprovide heat to cover 200 that accelerates regeneration ofmoisture-absorbing layer 206.

Liquid-impermeable layer 204 may comprise a woven material, a non-wovenmaterial or a combination of the two. A preferred vapor-permeablematerial for liquid-impermeable layer 204 is a laminate of 200 deniernylon inner layer and a breathable urethane outer layer, available fromLAMCOTEC Incorporated, Monson, Mass. Other vapor-permeable materials,such as expanded polytetrafluroethylene, GORE-TEX® fabric (W. L. Gore &Associates, Inc., Newark, Del.), SUNBRELLA® fabric (Glen Raven MillsInc., Glen Raven, N.C.), Hub Semi-Permeable fabric (Hub Fabric LeatherCompany, Everett, Mass.) or the like, may alternatively be used.

In an alternative embodiment, cover 200 may further include a heatingelement 212 that would allow moisture-absorbing layer 206 to regeneratemore quickly or regenerate when the conditions in ambient environment114 would otherwise not permit evaporation of the stored moisture. Sucha heating element may comprise an electrical resistance wire gridlocated within one of the layers or between adjacent layers.Alternatively, the heating element may comprise arrays of thin, flexibleheating elements consisting of etched-foil resistive elements laminatedbetween layers of flexible insulation like KAPTON®, NOMEX®, siliconerubber, or mica, or arrays of thin film ceramic elements available fromMinco Products Incorporation, Minneapolis, Minn. and Watlow Gordon,Richmond, Ill. among others (KAPTON® and NOMEX® are registeredtrademarks of E.I. DuPont de Nemours and Company, Wilmington, Del.).

In another alternative embodiment, the cover may further include a VaporCorrosion Inhibitor (also known as “Volatile Corrosion Inhibitor”) (VCI)214 incorporated into one or more of layers 202, 204 and 206, preferablyin the fiber matrix the moisture-absorbing layer, or into an additionallayer. VCIs 214 are volatile compounds that emit ions that condense onmetallic surfaces to form a mono-molecular layer that interacts withcorrosion agents to protect the surface. VCIs 214 are continuouslyself-replenishing and environmentally benign. Examples of VCIs that maybe used with the cover of the present invention include mixtures ofmaterials selected from amine salts, ammonium benzoate, triazolederivatives, alkali dibasic acid salts, alkali nitrites, tall oilimidazolines, alkali metal molybdates, and the like which can besupplied by Cortec Corporation, St. Paul, Minn., Daubert Coated ProductsIncorporated, Westchester, Ill., Poly Lam Products, Buffalo, N.Y.,Mil-Spec Packaging of Georgia Incorporated, Macon, Ga., and James DawsonEnterprises Limited, Grand Rapids, Mich., among others.

The addition of a VCI 214 to cover 200 enhances the corrosion inhibitingability of the cover by allowing the cover to continue to provideprotection when the moisture-absorbing layer is overwhelmed. Inaddition, the VCI 214 benefits from moisture-absorbing layer 206 becausethe moisture-absorbing layer removes the burden from the VCI by notrequiring it to offer protection at all times. One or more VCIs may beadded to any embodiment of the cover of the present invention, such asthose shown in FIGS. 4-7.

The layers of cover 200 are preferably bonded to one another throughoutarea 108 of cover 200 in a manner that does not interfere with itsliquid and vapor transport features, yet retains the layers in physicalproximity to one another. Bonding processes known in the art may be usedto bond or join the layers of cover 200. Bonding processes such asthermal bonding or multi-component adhesive bonding could be used tobond individual layers or the entire cover 200. Other bonding processesknown in the art, however, may be used. Alternatively, the layers may besecured to one another by other means such as stitching. Depending onthe size and materials of the cover, it may only be necessary to providestitching adjacent peripheral edge 106. Otherwise, it may be necessaryto provide quilt-stitching throughout the area. In a further alternativeembodiment, liquid-impermeable layer 204 may be removably secured to theother two layers 202 and 206 to allow it to be removed to speedregeneration of the moisture-absorbing layer. Re-fastenable fasteners,such as hook-and-loop fasteners, snaps, zippers and the like, may beprovided to facilitate this feature. Additionally, themoisture-absorbing layer 206 could be bonded or formed via an airlaidprocess known in the art as a process of producing a nonwoven web offibers in sheet form where the fibers are transported and distributedvia air flows where the entire sheet is then set with a mixture ofbinders and resins.

FIG. 4 shows another specific embodiment of corrosion inhibiting cover100 of the present invention, which is identified at 300. Cover 300comprises the three basic layers of cover 200, shown in FIG. 3, i.e., aliquid-permeable layer 302, a liquid-impermeable layer 304 and amoisture-absorbing layer 306 (these layers being identical,respectively, to layers 202, 204 and 206). In addition to these layers,cover 300 further includes a radar-influencing layer 308.Radar-influencing layer 308 may comprise a radar-absorbing material 310,a radar-reflecting material 312 or a combination of both, depending uponthe desired radar profile of cover 300. With reference to FIG. 2, it maybe preferable to have entire area 108 of cover 300 be radar-attenuating.For example, in a military application it may be necessary to reduce theradar profile of a large object to conceal its identity. On the otherhand, it may be preferable to have entire area 108 be radar-enhancing.For example, in a civilian application it may be advantageous toincrease the radar profile of a small water craft to accentuate itspresence. In another instance, it may be desirable to provide area 108with alternating discrete radar-attenuating and radar-enhancing regionsto give the cover a custom radar profile.

Although radar-influencing layer 308 is shown located betweenliquid-impermeable layer 304 and moisture-absorbing layer 306, it may belocated elsewhere. For example, the radar-influencing layer may belocated between moisture-absorbing layer and the liquid-permeable layer,adjacent outer surface 102 of cover 200 or the like. In addition,radar-absorbing material 310 and radar-reflecting material 312 may beincorporated into one or more of liquid-permeable layer 304,moisture-absorbing layer 306 and liquid-permeable layer 302. Care mustbe taken, however, to select a material that does not interfere with thevapor and liquid transport features of cover 300.

Radar-absorbing material 310, may comprise polypyrrole-coated polyesterfibers or the like which may be made into a thread that is then woveninto a discrete fabric layer or the outer layer. Such textiles areavailable from Milliken & Co., Spartanburg, S.C. under the trademarkCONTEX®. Alternatively, radar-absorbing material 310 may comprisediscrete particles of graphite or the like dispersed within the fibermatrix or within a coating that is applied to liquid-impermeable layer304 or is applied to a separate layer that is then incorporated into thecover. Other examples of radar-absorbing materials are REXradar-absorbing mats (Milliken & Co., Spartanburg, S.C.) and RFWPWeatherproof Foam (R&F Products, Inc., San Marcos, Calif.). Similartechniques may be used for radar-reflecting material 312, except that ametal or the like, which may be provided as a thread or as discreteparticles is incorporated into one or more layers of cover 300.

Referring now to FIGS. 2 and 5, there is shown yet another corrosioninhibiting cover 100 of the present invention, which is identified at400. In FIG. 5, cover 400, which has a five layer construction, is shownwith its peripheral edge 106 contacting surface 112, such as a ship'sdeck, a tarmac or the like. In such applications, it is common for alarge amount of liquid water to be absorbed by cover 400 at regionsadjacent peripheral edge 106. This is so because much of the water fromambient environment 144, such as rain, sea spray, dew and the like,repelled by area 108 travels down the sloping portions of cover 400,ending up adjacent peripheral edge 106. In order to prevent saturationof cover 400 in regions adjacent peripheral edge 106, additional layersmay be added to the basic three layer structure of FIG. 3 to provide aseparate zone for absorbing and storing moisture that may accumulate onsurface 112.

Accordingly, cover 400 includes an outer liquid-impermeable layer 402, afirst moisture-absorbing layer 404, an intermediate liquid-impermeablelayer 406, a second moisture absorbing layer 408 and a liquid-permeablelayer 410, which are located adjacent one another in the named order,except at a stepped region adjacent peripheral edge 106. The primarypurpose of outer liquid-impermeable layer 402 is to prevent liquidwater, such as rain, sea spray, dew and the like, from penetrating intothe micro-environment beneath cover 400. Outer liquid-impermeable layer402 includes a return to provide a robust structure at peripheral edge106. The primary function of first moisture absorbing layer 404 is toabsorb and store moisture that collects on surface 112, whereas theprimary function of second moisture absorbing layer 408 is to absorb andstore moisture trapped in the micro-environment beneath cover 400.

Intermediate liquid-impermeable layer 406 prevents liquid moisturestored in each of the moisture-absorbing layers from migrating to theother of such layers. At regions adjacent peripheral edge 106, thisseparation prevents second moisture-absorbing layer 408 from becomingover-burdened by moisture from surface 112. Preferably, bothliquid-impermeable layers are vapor permeable to allow cover 400 topassively regenerate by losing stored moisture to ambient environment114 when conditions there permit.

Peripheral edge 106 of the intermediate liquid-impermeable layer 406 islaterally spaced from peripheral edge 106 around the entire periphery ofcover 400 to define an opening 412. When cover 400 is draped over anobject, such as metallic block 110, opening 412 contacts or is slightlyspaced from surface 112, allowing any moisture present on surface 112 tobe wicked into first moisture-absorbing layer 404. Depending on designparameters, such as materials selected, volume of moisture to beabsorbed and the like, the width 414 of opening 412 may be variedaccordingly.

FIGS. 6 and 7 show a corrosion inhibiting cover 500 according to thepresent invention, wherein cover 500 is panelized into a number ofdiscrete panels, each denoted 502, and having an outer surface, an innersurface and a peripheral edge. Panels 502 are removably secured to oneanother, and are removably securable to other panels (not shown) ofsimilar construction, with fasteners 504 located adjacent the peripheraledge of cover 500. Panelization allows cover 500 of the presentinvention to be assembled to fit the size and shape necessary for aparticular application. To further enhance customization, one or more ofthe panels may be formed into a shape other than the rectangular shapesshown in FIG. 6.

Fasteners 504 may be of the hook-and-loop type, which includes aflexible hook strip 506 secured to the outer surface of cover 500 and aflexible loop strip 508 secured to the inner surface. Loop strip 508 ispreferably liquid-permeable so that its presence does not interfere withthe moisture absorbing properties of cover 500 at its peripheral edge.Such hook-and-loop fasteners may be VELCRO® brand hook-and-loopfasteners (Velcro Industries B. V., Curacao, Netherlands) or the like.Alternatively, other fasteners such as buttons, zippers, snaps, hook andeyelet, eyelet and lacing or the like, may be used for fasteners 504.

In the embodiment shown, each panel 502 comprises the basic three-layerstructure of a liquid-impermeable outer layer 510, a moisture-absorbinglayer 512 and a liquid-permeable inner layer 514. Alternatively, eachpanel 502 may be modified to include the plural moisture-absorbing layerstructure shown in FIG. 5 and/or the radar-influencing layer 308 shownin FIG. 4.

Although the invention has been described and illustrated with respectto the exemplary embodiments thereof, it should be understood by thoseskilled in the art that the foregoing and various other changed,omissions and additions may be made therein and thereto, without partingfrom the spirit and scope of the present invention.

What is claimed is:
 1. A cover for inhibiting corrosion of a metallicobject comprising: a. a first layer having a first face and a secondface, said first layer comprising a super-absorbent material adapted toabsorb and store moisture; b. a second layer located adjacent said firstface of said first layer, said second layer being liquid-permeable andmade of a woven material, a non-woven material, or a knitted material;c. a third layer located adjacent said second face of said first layer,said third layer being liquid-impermeable; and d. a vapor corrosioninhibitor region located within or adjacent at least one layer selectedfrom the group consisting of said first layer, said second layer andsaid third layer, said vapor corrosion inhibitor region comprising avapor corrosion inhibitor.
 2. A cover of claim 1 wherein saidsuper-absorbent material is a hydrogel.
 3. A cover of claim 1 whereinsaid first layer further comprises a fiber matrix.
 4. A cover of claim 3wherein said super-absorbent material is dispersed throughout said fibermatrix.
 5. A cover of claim 4 wherein said super-absorbent material is ahydrogel.
 6. A cover of claim 1 wherein said third layer is vaporpermeable.
 7. A cover of claim 6 wherein said third layer comprises anexpanded polytetrafluoroethylene material.
 8. A cover of claim 6 whereinsaid third layer comprises a laminate of a woven fabric layer and abreathable urethane layer.
 9. A cover of claim 1 wherein said thirdlayer is removably secured to said second layer.
 10. A cover of claim 1wherein said vapor corrosion inhibitor is contained in at least onelayer selected from the group consisting of said first layer, secondlayer and third layer.
 11. A cover of claim 1 wherein said vaporcorrosion inhibitor is located in a region separate from said firstlayer, said second layer and said third layer.
 12. A cover of claim 1further including a heating element located within said cover.
 13. Acover of claim 12 wherein said heating element comprises an electricalresistance wire located between said second and said third layers.